The proponents of drug and alcohol testing advance several safety and productivity arguments in support of their position. It is asserted that persons who test positively for drug and alcohol at the workplace experience higher levels of absenteeism and use sick leave to a much greater extent than non-users. Moreover, it is claimed that they have levels of productivity from 10 to 60 per cent lower than persons who do not test positively for drugs or alcohol. Perhaps the greatest argument advanced by those in favour of testing, however, is the safety element. Persons who abuse drugs or who consume alcohol to excess are involved in significantly more accidents than those who test negatively. In other words, proponents take the position that persons who test positively for the presence of drugs or alcohol form a category of individuals and that being in this category is grounds for labelling them as problematic employees. Moreover, so the reasoning goes, the only way to find out if an employee is a member of the category of drug or alcohol users is to test. Opponents of alcohol testing feel that the goal of ensuring a drug- and alcohol-free workplace is reached at too high a social cost and that the testing process constitutes an unwarranted invasion of the privacy of the individual. The provision of urine for analysis is a search, which, if conducted without consent or reason, would constitute an assault. Some opponents to testing feel that the real motivation for testing is controlling employee behaviour. Enterprises impose behavioural constraints on employees that may extend to off-duty times. Moreover, it is advanced that the testing process itself is humiliating to many people. In order to obtain a sample for testing, the person being tested must urinate in the presence of an attendant or supervisor. Often, medical standards are not used. Another moral issue is the implication of discrimination as a result of drug or alcohol testing. Perhaps the greatest concern is the systemic discrimination against disabled persons, persons with acquired immunodeficiency syndrome (AIDS), visible minorities and pregnant women that testing may engender. Again, different countries have addressed the discrimination issue in varying ways. Finally, opponents to drug and alcohol testing question the need to test. It is asserted that all testing shows is that, at some point in time, the person being tested ingested the screened substance.(ABSTRACT TRUNCATED AT 400 WORDS)